Empennage


  • Build delays and moving the airplane
    Empennage Section 10
    Jul 27, 2018

    I've had a 4 month hiatus from the plane with work being crazy and moving to a new house. The plane has made it to its new home safe and sound, and the workshop is slowly getting set up again. Now the build resumes!


  • Bucking bar damage
    Empennage Section 10
    Apr 13, 2018

    Before I fabricated an alignment guide to keep the bucking bar perfectly perpendicular, I managed to nick the J-channel in a few places which left a healthy dent that was barely visible on the exterior, but definitely on the interior. I was a bit concerned that this would be a structural issue, and was prepared to drill out all the rivets and replace the channel completely. After consulting Vans however, they recommended to buff out any sharp edges and build on, so that's what I did.


  • Starting tailcone
    Empennage Section 10
    Aug 27, 2017

    This particular section has been taking some time for me with work getting busy, but I'm finally getting around to writing it up. There's a bit of fabrication you have to do for the rudder stops by cutting up some angle stock. I somehow got the measure twice cut once rule backwards and frustratingly had to order a replacement but the second round turned out pretty well.

    Next is getting all the bulkheads riveted with heavy aluminum reinforcements to attach the tail components. These guys were a pain to deburr with all their complex corners and tabs. The squeezer could reach almost all the rivets so I was happy about that.

    In putting the large components together, there was a ton of dimpling and countersinking to do first. Then you start riveting the bulkheads, J-channel stiffeners, and longerons to the skins, which is exciting as you start to get a sense for the scale of the aircraft.

    Here's where I had my first bucking bar incident where the bar slipped off the rivet, and hammered a bad crease into one of the J-channels and the corresponding skin behind it. I did my best to hammer the skin flat again, but the J-channel had to be drilled out and replaced.

    Attaching the side panels was fairly straightforward, but there is a lot of riveting to do here. Some of it is easy, some are pretty hard to reach without two people. Most frustratingly for me was the aft most section where you can barely fit your hand inside to hold the bar. I found that I would inexplicably dent the skin with the rivet gun once in a while and I really couldn't figure out why. Best current theory is that I wasn't able to provide enough back pressure on the bar. I purchased a cheap dent removal tool from ebay to experiment with pulling some of the dents out, but it really wasn't very effective. I'll probably play a bit more with finding ways to smooth these out later as dents drive me crazy.


  • Elevator trim tab complete
    Empennage Section 9
    Jul 13, 2017

    The elevator trim tab took surprisingly long to complete, given its size and apparent complexity. First was a fair bit of countersinking through material that is right on the threshold of too thin in my opinion. When countersinking the spar with the hinge cleco'd to the backside, the countersink essentially went completely through the spar and just touches the hinge. A new element I haven't used in the build so far was the use of foam ribs that had to be adhered to the aluminum skin with ProSeal, which is a bit of a mess to work with. First the contact surfaces need to be scuffed and cleaned.

    You mix the ProSeal at a ratio of 10:1 by weight, which was actually a bit challenging given the goopyness of both the accelerator and the base. I hear this stuff doesn't have that long of a shelf life, and I'd like to use it for the wing when I get to it, so now it's sitting in my fridge. Then I clamped it all together and riveted the spar, skin, and hinge together.

    The rivets along the hinge were the hardest part, as a squeezer could barely fit in there, and the rivets were so long that it was extremely hard to get them to compress straight. I probably ended up drilling out half of the rivets due to this. I've found one of the side effects of drilling out rivets through sandwiched material is that it's easy to start creating space between the layers that you can't compress back down. I ended up with a few small pockets of space underneath the hinge that I'm not too happy about. I've flagged it to show to a tech councilor, and may have to redo it. Furthermore, despite doing most of the riveting clamped to a steel beam that I know is perfectly straight, the tab ended up with a very slight bow, but no twist. I'll have to see how well it attaches to the elevator afterwards, but it annoys me slightly.

    The rivets along the hinge were the hardest part, as a squeezer could barely fit in there, and the rivets were so long that it was extremely hard to get them to compress straight. I probably ended up drilling out half of the rivets due to this. I've found one of the side effects of drilling out rivets through sandwiched material is that it's easy to start creating space between the layers that you can't compress back down. I ended up with a few small pockets of space underneath the hinge that I'm not too happy about. I've flagged it to show to a tech councilor, and may have to redo it. Furthermore, despite doing most of the riveting clamped to a steel beam that I know is perfectly straight, the tab ended up with a very slight bow, but no twist. I'll have to see how well it attaches to the elevator afterwards, but it annoys me slightly.

    In the mean time, onward to working on the rest of the elevator!


  • Elevator horn alignment
    Empennage
    Jun 23, 2017

    After checking measurements and alignments multiple times between the elevator horns and the corresponding ribs, I'm convinced the E-905 rib at the root of the left elevator is mispunched. Measuring the right-side E-00906-1, there's about a 3/32" difference in the hole centerings compared with the E-905. As a result, the horn doesn't even come close to fitting on the left side, but the right side lines up perfectly. Now I'm awaiting to get another response from Van's to see what to do about it.

    Update #1: I got a reply from Van's and indeed the rib is mispunched. Supposedly some other RV-14 builders had similar issues. They mailed out a new rib very quickly, but unfortunately they sent the wrong one :( I'm now waiting again to hear back from the service department.

    Update #2: After calling Van's, it was no problem to have them ship out a new E-905 rib. They covered the cost again, and were very friendly about it. The annoying part was that I had to reprime this rib. I am starting to really hate the process of priming parts. The time it takes to scour, degrease, dry, wipe down with alcohol, mix the primer, prep the spray gun, prime, and cleanup takes half a day. That and half of my parts always end up with some orange peel which annoys me to no end. I should probably revisit my spray gun setup, because clearly something isn't quite right. At any rate, I decided to clean up and deburr all the remaining parts in the empennage to prime them together which was a major pain, but hopefully saves me some time in future.


  • Refolding closeout tab
    Empennage Section 9
    Jun 23, 2017

    To deal with my previously botched fold on the closeout tab on the elevator here, I got a response from Van's that suggested to fabricate a new closeout tab from the same type and thickness of material. After putting some thought into this, I couldn't figure out a way to cleanly fabricate one and get it attached flush with the existing tab. Instead, I decided to try and hammer out the existing fold, and refold the tab in the correct position. If it failed miserably, I would just purchase a new skin from the factory.

    I used a backriveting plate and a flush rivet set to hammer out the crease of the previous fold, then used the edge of the same backriveting plate to make a new fold. It actually turned out a little better than I was expecting, albeit my expectations were fairly low. There's still a noticeable blemish between the two creases, but I think I'll actually keep it and hope it gets hidden by the paint.


  • Starting elevator
    Empennage Section 9
    Jun 20, 2017

    The elevator is a surprisingly long section, so I tried to pull out all the components and get them prepped and primed first. What a pain in the butt this is between cleaning, degreasing, scuffing, priming, and all the resulting cleanup of the HVLP gun. It probably took me a half day for one table of parts.

    For my last attempt at priming, I took the advice of only putting on enough paint to just notice a change in coloration (I'm using SW-P60G2). In the end, I think it was much too thin. This time I put it on much heavier, and I think they came out much better. At least it's a noticeable green, as opposed to the barely tinged silver from before. I also reduced slightly less than 200% to about 175%.

    It was inevitable that I missed a part, however, and it had to be a big one like the trim tab spar. Oh well, I guess I'll collect all the tailcone parts soon and try to prime the whole lot next.

    Everything seemed to be going fairly swimmingly until I got to match drilling the closeout tab on the skins near the trim tab. There's about a 1/4" gap from where the shear clip is and where the skin closeout should be. Doh! Not sure how to compensate for this one, so awaiting some feedback from Van's again.


  • Rudder finished
    Empennage Section 7
    Jun 7, 2017

    Got the lead counterbalance installed in the rudder. Not sure if I'm just being paranoid but I'm totally not touching that with my bare hands!

    I've heard of people using ProSeal to fix the nuts on the interior of the counterbalance since there's no access once everything is riveted together. I actually don't have any ProSeal yet, so used Loctite instead before torquing the bolts down. Fingers crossed they don't back out or that's going to be a mess to fix.

    For the trailing edge, I made sure that everything was perfectly straight when getting everything cleco'd together, and indeed it was almost perfect as-is.

    My perhaps less-than-brilliant scheme to keep it that way was to use a steel square beam I found at the hardware store as a backrivet plate, which was also perfectly straight when I bought it.

    I used a standard flush rivet set on the front face. It turns out the force of backriveting just knocks giant dents into the steel, and leaves the trailing edge with a small indent and a bad rivet that needs to be drilled out. So much for that idea.

    Instead, I used some extra aluminum wedge-stock that was used for the trailing edge as a backing plate such that I had 2 parallel faces to use the squeezer. The aluminum stock definitely took some damage and the manufactured heads ended up slightly rounded, but at least the rivets were consistent and cleanly fastened. I alternated sides between rivets, which is what everyone seems to do for aesthetics, but honestly I think it would be more consistent to have all the shop heads on the same side. The resulting trailing edge wasn't quite as perfectly straight as I hoped, but at least there's no warp in it. I'll attempt to use a tool to get out the wavy sections at some point and hopefully straighten it out some more.

    One thing that I forgot to do was to rivet the flanges on the outside rib before closing up the trailing edge. This left me with basically zero room to get any kind of bucking bar in there. In fact, it was so narrow that the rivet couldn't even be fully inserted without hitting the shop head of the rivet on the other side. I purchased some steel chisels from the hardware store that were angled enough to slip it behind the rivet to serve as a makeshift bucking bar, and it shouldn't be a surprise that it didn't really work. This ended up with a cracked rivet. I'm currently leaving it as-is, because I don't think I can do any better at bucking that rivet. I may drill it out and use a flush blind rivet instead, however, which is what I should have done in the first place.

    In the mean time, I'm a few rivets shy near the corners by the horn where I need to find a specialized bucking bar with a toe, but otherwise I think the rudder is complete. On to finishing the horizontal stabilizer!


  • Horizontal stabilizer
    Empennage Section 8
    Jun 6, 2017

    While in principle the horizontal stabilizer build should be pretty straight forward, I definitely made several aspects of it way more difficult than it needed to be. First was in countersinking the spar flanges. Supposedly the stops on most countersink cages are .001", and convention is to drill until the rivet sits flush, then stop in .007" further to accept a dimple. Supposedly a 112-degree countersink bit is ideal, but everyone seems to only have the standard 100-degree bit. Nevertheless, it felt like I had to countersink far deeper than that to get an acceptable flush mating between the skin and the spar and I still don't have a great explanation why.

    After dimpling the skins, riveting in the rib tips, and attaching the front spar I notice this...

    Yep, I riveted in the spar with 36 missing rivets on the spar caps that are now inaccessible from the back side. Bah! I decided I wasn't willing to drill out all the flange rivets, and contacted Van's support to get some options. They said putting Cherry Max rivets would be just as strong, and an easy fix right? I purchase CR3213-4-5 rivets to replace the AN470AD-5 that should have been in there and installed them with a little bit of flexing of the inspar ribs and some chewed up knuckles from scraping against the dimples while operating the rivet puller. Afterwards, while riveting the remaining flange rivets I notice the Cherry Max rivets were starting to back out. I went to the Cherry specifications, and it turns out the grip size on the 4-5 rivets are way too large and they weren't remotely fastened from the backside. Aaargh again. Now the challenge of drilling them out. My first attempt was to drill it out like any other rivet, so I got a 12" long #30 bit and tried to center it as much as possible. It turns out this is extremely difficult, as the Cherry rivets have a steel center section where the mandril goes through, and it's really quite hard. I dulled my bit rather quickly, and just made a mess of the rivet. My next attempt was to use a small high speed cutter bit on a Dremel to grind off the head. This was working okay, but due to the really tight working space it was difficult to navigate in there and get any precision. Needless to say the tool slipped, and I made a nice nick in the spar:

    I contacted Van's support again, and this is the first time they didn't have a clear answer for me. It's "probably okay" they said, but it's in a grey area of not being able to guarantee the impact on the spar's strength. I tried my best to measure the depth of the nick, and I think it's under 10% the thickness.. so I decided to scotchbrite the sharp corners off and continue. Furthermore, it's about midway from the center near where they cut out the lightening holes in the spar. Fingers crossed it doesn't become an issue.

    Now back to the issue of drilling out the Cherry rivets. As usual, and found some inspiration from the VAF forums, which suggested to punch out the mandril first. I went out to Harbor Freight and purchased some cheap punches I didn't care about destroying, and a tiny hammer, and attempted to hammer out the mandrils from the center. Needless to say, they're pretty stuck in there. I'll repeat what many have already said.. but these Cherry rivets are definitely robust. What ended up working pretty well is attaching the punch to a flush rivet set using some heavy tape, and punching out the mandril (plus the steel sheath) using the rivet gun. This actually worked fairly brilliantly. Afterwards, there's just a bare aluminum rivet with a nice hole in the middle that can be drilled out with a #40 bit no problem.

    I purchased the correct Cherry Max rivets (always check the grip size before ordering them!) and got them installed. Phew!

    Next hiccup was when riveting the skins to the flanges, I noticed I somehow missed dimpling about a dozen of the holes. There are so many rivets already fastened that I can't imagine taking it apart, so now I'm trying to improvise how to get it dimpled with the rivet gun. I've heard of people doing it.. so I improvised an attachment to the gun that would accept the male die, and placed the female end into a piece of wood backed by a bucking bar.

    This indeed made a dimple, but it's a little bit too shallow - and there's a noticeable indent in the skin that's distinct from the nice flush appearance from the DRDT2 dimples. Once riveted, the rivet protrudes out ever so slightly due to the shallow dimple. It's just cosmetic.. but it totally bothers me. 

    Everything else went fairly according to plan. Riveting the interior rivets is definitely a challenge and any slip-up will earn you a nice smiley shaped dent in the skin that will infuriate any detail-oriented person. I purchased one of those rubber cupped swivel rivet sets, but noticed that they can easily leave the manufactured head raised up from the skin due to the stiff rubber cup. Instead, I decided on using the standard rigid mushroom set that makes much more solid contact but seems to have almost no tolerance for error. I think I ended up having the gun bounce on two rivets leaving a small smiley on each one, which resulted in much cursing and swearing.

    One of them was rather bad, so I made some attempts at hammering it out. The smiley is largely gone, but the area is noticeably rougher now. Hopefully it will be less noticeable when painted.

    Last step was to attach the rear spar, and all the edge rivets could be squeezed which is super easy compared to riveting with the gun. I'll elect to use the squeezer any time it will fit. Now on to the elevator!


  • Rudder skin dimpling
    Empennage Section 7
    May 29, 2017

    I didn't like how the DRDT2 recommended building the side tables, so I decided to concoct something else. I ended up using the wood from the empennage crate (it was a pain to get all the staples out, but almost all of the wood has been useable for something involved in the build). I drilled a hole where the bottom dimple die goes, and cut slots in the legs for the frame to go through. It's sturdy and seems to do the job.

    I had to experiment a bit with whether to have the female dimple die on the top or bottom. If it's on the top, the sheet slides nicely on the table surface as the dimples are facing upwards, but it's easy to get it scratched up if you're not careful with the male die on the bottom. Instead, I chose to have the female die on the bottom so I didn't have to worry about constantly lifting the sheet, but it does chew into the wood a bit and creates some sawdust.


  • Rudder stiffeners
    Empennage Section 7
    May 29, 2017

    The rudder requires that you trim off or separate all the stiffeners to get the ends to taper off to a point. I tried to use snips at first, but it doesn't really work at all. Afterwards I broke down and purchased a cheapy band saw, put a metal blade on it, and it works great cutting sheet aluminum.


  • Vertical stab done
    Empennage Section 6
    May 29, 2017

    It took quite a bit of time to decide on a primer and get everything ordered and delivered, so I ended skipping through sections every time something was held up because it needed to be primed. Afterwards, I was able to revisit the vertical stabilizer, and it came together rather nicely without any issues.

    Seemingly any time there is a rib with reasonable curvature, the plans calls to flute the flanges if needed. It isn't entirely clear to me when it's needed, as most of the flanges that I've come across seem to sit pretty flush with the skin after simply getting them at the right angle. Furthermore, all my attempts at using a fluting tool seems to just bend the flanges up and make it worse. Instead, I 3D-printed a little 90-degree alignment and bending tool that seems to work pretty nicely in getting the flanges nice and square. I'll try to put up a section to download all 3D printed tools I've come up with.


  • Vertical stabilizer build getting started
    Empennage Section 6
    May 14, 2017

    The vertical stabilizer took me quite a bit of time to complete for several reasons. 

    First was simply figuring out the process for how to dimple and rivet in various places, some harder to reach than others. Second and more prominently was that I hadn't decided on how to deal with primer yet. Fairly quickly in the build you have to do final assembly of parts, which need to be primed if you choose to use primer. More on that later!

    For dimpling and riveting, I found that the pneumatic squeezer is a little more versatile than I originally thought. At first, I thought it was fairly useless because the most reliable/safe way to dimple or rivet is to place the manufactured head on the far end of the yoke so that the piston compresses the shop head or female die. Other than on the edges of flat skins, however, it's rare you can get the squeezer into this position since most of material that needs riveting is on an outside flange where the body of the squeezer and the material your working with gets in the way of each other. If you reverse the squeezer dimple dies but keep the material flush now on the female side, then it's really difficult to keep the material aligned such that the pilot hits the hole perfectly centered. I found this is a great way to punch unintended holes into parts, and should in general be avoided.

    If you put the material flush against the female side on the interior of the yoke, this causes the squeezer to jump back when you pull the trigger because the piston is pushing the assembly forward. It wasn't completely obvious from the squeezer manual that the piston could be throttled by having a light touch on the trigger. It definitely takes a bit of practice, but it makes the squeezer useful in so many more scenarios. There's still a few cases, like in the image below, where there's not a lot of room for error and I kind of had to try my best to line it up then hit the trigger and pray. I'm almost tempted to get a mechanical hand-squeezer for places that require good control if they weren't $300.


  • Shipment
    Empennage
    Apr 1, 2017

    So far, my experience with Van's has been rather pleasant. The people at sales have been helpful, crating and shipping was prompt, and the empennage kit arrived very nicely packed without any discernible damage.

    It took me about 3 hours to inventory everything. Everything was clearly tagged, and the included materials list was easy to follow. I had a few items that were marked as b/o (backorder), and I assume they will arrive in the mail shortly. None of the backordered items are needed for the initial steps, so this isn't a hindrance at all.